I got these today, they seem like they would be really nice boots and comfortable, if your foot is more on the narrow side. For my size 12.5 feet that usually fit M width perfectly fine, I found the toe box to be a bit narrow with normal socks, and getting tight with a pair of boot socks. I might have lived with them if I wanted to wear regular socks (still would have been a bit snugger than I would have liked), but that kind of defeats the purpose. The length was fine for my 12.5 feet, I have a feeling a 13 might have been a bit snug. I'm wondering how a size up would fit. Anyway I am sending them back. The four star review is due to the fact that they seem like really nice boots that could be quite comfortable, but are a bit on the small/narrow side. If you foot runs on the narrower side of a meduim width you would likely be ok, but you might want to size up on length.

Answer
Sorry there is not a temperature rating. Most manufacturers do not have temperature ratings for their garments or footwear due to the number of factors that affect how warm a garment may keep you.